Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Residential mortgage principal balance repurchase request received	$ 543	$ 543
Residential mortgage principal balance FHLB credit enhancement	80,000
Residential mortgage repurchase reserves FHLB credit enhancement	1,100	1,200
Sale of non-prime loans	44,900
Unpaid principal balance	58,400
Reserve for Off-balance Sheet Activities [Member] | Residential Mortgage [Member]
Loss Contingencies [Line Items]
Valuation allowances and reserves, balance	$ 2,100	$ 2,100